The detection of a cell surface antigen by its specific reactivity with an antibody can be performed in several ways. Immunofluorescence staining, radiobinding assays, agglutination assays and complement-mediated cell lysis are the most commonly used methods. In all these procedures, the determination of the reactivity of the cells with each antibody is handled separately, i.e. the cells are incubated separately in a tube or in a well of a microwell plate, etc. with each antibody to be tested.
In U.S. Pat. No. 4,591,570, an immunoassay device, called an "antibody matrix" device, is disclosed which allows simultaneous determination of specific cell surface antigens in one reaction incubation by employing orderly arranged antibody spots on a solid surface. It was demonstrated that when an antibody-coated surface is used for the adsorbence of cells, reactive cells adhere microscopically uniformly over minute areas in different parts of the solid surface. Because of this property, antibodies of distinct specificities are coated on small, discrete areas in close proximity forming a matrix-like array on the surface. The spots act as tiny specific immunoadsorbents for cells bearing on their surface the antigens with which the antibodies react.
"Antibody matrix" devices can be used not only to determine the presence of a specific allotype of a surface antigen on the cells of an individual (such as tissue typing), but also to analyze functionally different cell subpopulations that express distinct differentiation antigens. The antibody-coated surfaces can adsorb quantitatively from a mixed population the cells that bear the specific cell surface antigen the antibody react with. Thus, the device can be used to determine the proportion of specific subsets in a mixed population of cells.
The "antibody matrix" device represents a major simplification of existing immunocytological and immunochemical methodology in that it eliminates the need for repetitive pipetting when a large number of tests for different antigens are performed. Other advantages are that all tests with antibodies may be performed simultaneously in one location, only a single application of sample is required as opposed to the repetitive pipetting of sample into a large number of separate wells or tubes, and very small amounts of sample and reagents are consumed.